I have twin 2001 Yamaha F115 outboards and both are experiencing idle problems. Initially, once the engines would crank, they would only idle 5 seconds max before dying. If I could keep them running, I could get them up to about 3500 RPM, but the boat would not plane. If it did plane, it took a long distance and maybe reach 3800 RPM. Once I pulled the throttle back to neutral the engines would instantly die. I have done several things to fix this which I will list below, but I am still having problems.
1.) Replaced inline fuel filters and fuel/water separators.
2.) Replaced VST filters.
3.) Sent all fuel injectors off for testing and cleaning.
4.) Replaced spark plugs.
5.) Replaced thermostats.
6.) Replaced ISC valves.
7.) Checked the mechanical lift pumps.
I tested the mechanical lift pumps the best I could. I removed the outgoing hose and unbolted it from the engine. With my finger over the outlet, I pumped the bubble until it was hard. I waited a few minutes and the bubble stayed hard and no leaks. As I removed my finger gas would spray a good ways from the pressure. Next, as the engines were running I tried squeezing the bubble to mimic the pump. That made no difference. Lastly, I put a hose on the outlet side of the pump and put the other end in a gas can. Using the ignition switch it turned over the engines. It appeared to be pumping plenty of fuel. I'm not sure if any of those "test" gave a true answer to whether or not the pumps are working.
Currently, once started, the engines will run perfectly for about 5 to 10 seconds then start skipping. Run rough for another 5 to 10 seconds then die. Used to, the engines would fire almost instantly, now it takes turning them over for about 3 seconds before they fire. One engine runs wide open at approximately 5300 RPM while the other is around 4800 RPM. This is compared to both running around 5600 RPM before this issue started.
All I know to do next is to get the boat to the local Yamaha tech and have them run diagnostics, but due to several circumstances it has proven to be very difficult to do so. In the mean time, does anyone have any suggestions for something to try/check next?
Thanks in advance for the help.
1.) Replaced inline fuel filters and fuel/water separators.
2.) Replaced VST filters.
3.) Sent all fuel injectors off for testing and cleaning.
4.) Replaced spark plugs.
5.) Replaced thermostats.
6.) Replaced ISC valves.
7.) Checked the mechanical lift pumps.
I tested the mechanical lift pumps the best I could. I removed the outgoing hose and unbolted it from the engine. With my finger over the outlet, I pumped the bubble until it was hard. I waited a few minutes and the bubble stayed hard and no leaks. As I removed my finger gas would spray a good ways from the pressure. Next, as the engines were running I tried squeezing the bubble to mimic the pump. That made no difference. Lastly, I put a hose on the outlet side of the pump and put the other end in a gas can. Using the ignition switch it turned over the engines. It appeared to be pumping plenty of fuel. I'm not sure if any of those "test" gave a true answer to whether or not the pumps are working.
Currently, once started, the engines will run perfectly for about 5 to 10 seconds then start skipping. Run rough for another 5 to 10 seconds then die. Used to, the engines would fire almost instantly, now it takes turning them over for about 3 seconds before they fire. One engine runs wide open at approximately 5300 RPM while the other is around 4800 RPM. This is compared to both running around 5600 RPM before this issue started.
All I know to do next is to get the boat to the local Yamaha tech and have them run diagnostics, but due to several circumstances it has proven to be very difficult to do so. In the mean time, does anyone have any suggestions for something to try/check next?
Thanks in advance for the help.